Method of and apparatus for grinding gears



INVENTOR ATTORNEYS 2 Sheets-Sheet l March 6, 1956 w. c. WHITTUM METHOD OF AND APPARATUS FOR GRINDING GEARS Filed March 15, 1954 March 6, 1956 w. c. WHlTTUM METHOD OF AND APPARATUS FOR GRINDING GEARS 2 Sheets-Sheet 2 Filed March 15, 1954 ATTORNEYS 2,736,994 METHOD OF AND APPARASTUST'FOR GRINDING GEAR Warren C.'Whittum, Anso'nia, Conm, assignor to Farrel- Birmingham Company, Incorporated, Armenia, Conn a corporation of Connecticut Applicationlviarch 15, 1954, Serial No. 416,173

20 Claims. -'((Il. 51-442) *This invention relat'es togear-grindingmachines and more particularly 1 to a device for grinding or finishing theteeth upon a gear blank by means of a traveling abrasive belt or other traveling flexible member either covered with abrasive or having abrasive or cutting or grinding members secured thereto.

Gearg'rinding machines which have been generally used -in the past employ rotary grinding wheels, the grinding wheels rotating on their own axes and being engaged with the surface ofa toothof the gear to be ground. With machines of this character, the grinding process is a relatively slow one as the grinding wheel can only engage local areas on the tooth to be ground, and it is,

therefore, necessary-for the machine to operate'through a combination of a rolling action to cover the curved portion of the tooth together with'a motion parallel to the length (width of the gear) of the tooth to cover 'the'whole face of thetooth.

In the gear grinding machine of the present'inv'ention a rectilinearly traveling belt-is employed, the operative portion of which travels parallel to'the axis of the gear 'so that it willgrind over the entire length of the face of the tooth'at one time, and it is therefore, only necessary to roll the gear relatively to the traveling belt to grind the entire face of the tooth.

This rolling motion may readily beobtained by the combination of a reciprocating movement imparted to the supporting mechanism for the traveling belt and arotary movement of the gear blank.

The apparatus may be so arranged that, if necessary, the grinding belt may travel over the surface of the gear a number of times if this is desirable in order to finish the gear, and thereafter provisionis made'for indexing the 'gear blank so as to present another tooth to the grinding belt. I

It will be understood that 'the'feature of actuating'the "grinding device'so that it travels in a rectilinear path 'paralle'lto the axis of the gear so as to contact the entire length 'of the tooth face is an important one in effecting a saving of time in the operation of finishing gears and ploying a traveling endless belt having grinding or abrasive material thereon. A similar result may, of course, be obtained by a longitudinally reciprocable belt or strap carrying some type of grinding or cutting elements such 'as abrasive material.

One object of thepresent invention is to provide a new and improved gear grinding mechanism.

Astill further object of the invention is to provide a gear grinding mechanism of simpler construction than those formerly employed and'one which will be capable United States PatentO of performing its work more rapidly than prior devices of this character.

Still another object of the invention is the provision of a gear grinding machine in which the grinding mechanism is actuated along the face of the gear tooth in a rectilinear path substantially parallel to the axis of the gear blank so that the abrasive or grinding elements contact the entire length of the face of the gear tooth during their passage across the tooth.

A still further object of the invention is to provide a 'gear'grinding machine wherein the grinding is performed by an endless traveling belt held firmly against the face of the gear tooth, the belt traveling in a path'substantially parallel to the axis of the gear.

Still another object of the invention is to provide a gear grinding machine of the character described above in which the supporting mechanism for the traveling grinding belt will be caused to reciprocate in timed relation with a movement of the gear blank about its axis so as to cover the entire curved surface of the gear tooth during the grinding operation.

To these and other ends the invention consists in the novel features and combinations of parts to be hereinafter described and claimed.

In the accompanying drawings:

Fig. l is a front elevational view of a gear grinding machine embodying my invention;

Fig. 2 is a plan view therof;

Fig. 3 is a vertical sectional view on line 3-3 of Fig. l with the abrasive belt and associated parts being shown in elevation;

Fig. 4 is a sectional view on line 4-4 of Fig. 3; and

Fig. 5 is a horizontal sectional view on line 5-5 of Fig. 1.

v To illustrate a preferred embodiment of the invention, I have shown in Fig. l of the drawings a gear grinding -mechanism comprising base or frame portions 10 and 11, the portion 10, as will be hereinafter described, serving as a support for the grinding mechanism, and the portion 11 serving as a support for the gear blank. A hollow shaft 12 is rotatably mounted by suitable bearings within the supporting base portion 11, this shaft carrying at its upper end a table or support 13 upon which the gear blank 14 is secured, as shown in dotted lines in Fig. 2.

Secured to the lower end of the shaft 12 is a bevel gear 15, which gear mesheswith a bevel gear 16 carried by a sleeve 17. This sleeve is rotatably mounted by suitable bearings 18 in the support 11, and secured to a projecting end of the sleeve is an indexing wheel 19.

The base 10 for the grinding mechanism is provided with parallel ways 21 upon which is mounted a reciproeating carriage 22. The reciprocation of the carriage may be effected hydraulically by means of a cylinder 23 carried by the support 10 and a piston rod 24 secured at 25 to the end of the carriage 22. It will, of course, be understood that suitable connections (not shown) are provided for introducing fluid pressure into the cylinder to effect reciprocation of the carriage over a path of the length desired depending on the dimensions of the tooth to be ground. The carriage may, of course, be reciprocated by means other than that shown without departing from the present invention.

A pin 32 is movably carried by a flange 33 of the indexing wheel 19, the inner end of the pin being received in one of the recesses 31 so as to connect the disk 30 with the indexing wheel 19. It will be understood that when it is desired to index the work table 13 so as to present a subsequent tooth to the grinding mechanism, the pin 32 may be withdrawn from the recess 31 and the indexing wheel 19 rotated with respect to the disk 39.

It will be understood that the particular indexing means shown is merely illustrative and that other suitable indexing means, either manual or automatic, may be provided if desired. With the pin 32 engaged with the disk 30, it will be apparent that the work table 13 will be actuated by the shaft 26 so that when this shaft is oscillated through the reciprocation of the carriage, as will be hereinafter explained, the table 13 is also oscillated to move the gear blank or the gear tooth which is engaged with the grinding mechanism in an arcuate path which is co ordinated with the reciprocation of the carriage.

The oscillation of the shaft 26 from the reciprocation of the carriage 22 is effected by means of flexible straps 3-6 and 37, one end of these straps being secured to the carriage as shown at 38 and 39 and the other ends being wrapped around a driving disk 40 and secured to the periphery thereof, as shown at 41 and 42. The disk 46 is secured to the shaft 26, and with this construction it will be apparent that as the carriage is reciprocated the disk 40 and shaft 26 will be oscillated thereby effecting oscillation of the work table 13 and the gear blank 14- carried thereon.

A tool support 43 is mounted upon the carriage 22 for movement transversely thereof so that the abrasive belt to be hereinafter described may be fed into the work. To this end an adjusting screw 44 is rotatably mounted in the tool support 43, this screw being threadedly engaged with a nut 45 secured to the upper surface of the carriage. The screw carries a hand wheel 46 by which it may be manipulated so that, as shown more particularly in Figs. 2 and 3, this tool support 43 may be moved transversely of the carriage toward and from the work-supporting table 13.

A tool carrier 47 is rotatably mounted upon the support 43, this carrier, as shown in Fig. 3, being provided with a spindle 4S rotatably mounted in a socket 49 in the support 43. This carrier 47 may be held in any adjusted rotative position on the support 43 by means of a locking screw t} having threaded engagement at 53 with the support 43 and passing through an arcuate slot 52 in the carrier 47, this slot being concentric with the spindle 48. As will be hereinafter explained rotative adjustment of the carrier 47 serves to present the grinding belt to the work at the proper angle.

Secured to the carrier 47 and extending upwardly and downwardly therefrom is a frame or standard 53 having bearings at its upper and lower ends for pulleys 54 and 55 about which is trained the abrasive grinding belt 56. At its upper end the frame 53 also supports an electric motor 57 for rotating the pulley 54 to drive the grinding belt.

As the belt 56 is an endless, flexible belt, backing means are provided to hold the belt firmly against the work, that is against the face of a tooth of the gear which is being ground. To this end the frame 53 is provided with forwardly projecting flanges (Fig. 5) 59 and 68, these flanges being disposed in the plane of the runs of the belt 56 and, as shown, serving to back up the belt and hold it firmly against the work. These flanges may be of any length desired but, as shown, extend substantially over the distance between the upper and lower pulleys 55 and 56.

In the operation of the device the carriage 22 may be drawn to the left, as shown in Fig. 2, so that the belt 56 is in the position marked A. It will be seen that in this position the belt will clear the adjacent tooth of the gear blank so that the latter may be properly indexed or brought to a position to be ground. By operation of the hand wheel 46, the tool support 43 may be moved forwardly to set the belt at the proper position and the tool carrier 47 may be rotated about its spindle 48 in order to set the belt at the proper grinding angle.

The machine may then be started and as the carriage reciprocates the work table 13 will be oscillated, thus carrying the grinding belt and the gear tooth from the dottedline position at A in Fig. 2 through the full-line position in this figure, and to or past the dotted-line position marked B, if desired. It will be seen that the entire curved surface of the tooth will be ground during this travel of the work carriage, and as the belt travels rectilinearly with respect to the face of the tooth, the entire length (depth) of the face of the tooth will also be ground. It will be understood that the table may be reciprocated as many times as is necessary to finish the grinding operation.

After one tooth has been ground, the carriage is moved to the left as previously explained, and the pin 32 will be removed from the disk 30, thereby enabling the operator to rotate the indexing wheel 19 and bring a following tooth into position to be ground. The indexing may, of course, be performed automatically.

It will be understood that the invention may be employed in grinding bevel gears and helical gears as well as spur gears and that the angular position of the abrasive belt may be changed for this purpose so as to travel along an element of the tooth surface to make line contact therewith.

While I have shown and described a preferred embodiment of my invention, it will be understood that it is not to be limited to all of the details shown, but is capable of modification and variation within the spirit of the invention and within the scope of the claims.

What I claim is:

l. The method of grinding gears which comprises moving a planar portion of a grinding element over the face of a gear tooth on a gear blank in a rectilinear path, substantially parallel to the axis of the blank, while rotating the blank about its axis, and effecting a translatory movement of the grinding element in a direction transverse to said rectilinear path in timed relation to the rotation of the blank.

2. The method of grinding gears which comprises moving a planar portion of a grinding element over the face of a gear tooth on a gear blank in a rectilinear path, substantially parallel to the axis of the blank, while rotating the blank about its axis, effecting a translatory movement of the grinding element in a direction transverse to said rectilinear path in timed relation to the rotation of the blank, and then indexing the gear blank with respect to the grinding element to bring a succeeding tooth into engagement therewith.

3. The method of grinding gears which comprises moving a flexible belt having abrasive elements thereon along the face of a tooth on a gear blank in a rectilinear path substantially parallel to the axis of the blank and simultaneously rotating the gear on its axis, and moving the belt in a direction transverse to the direction of its travel to maintain its engagement with the moving gear tooth.

4. The method of grinding gears which comprises mow ing a flexible belt having abrasive elements thereon along the face of a tooth on a gear blank in a rectilinear path substantially parallel to the axis of the blank and simultaneously rotating the gear on its axis, moving the belt in a direction transverse to the direction of its travel to maintain its engagement with the moving gear tooth, and pressing the belt against the face of the moving gear tooth.

5. The method of grinding gears which comprises moving a flexible belt having abrasive elements thereon along the face of a tooth on a gear blank in a rectilinear path substantially parallel to the axis of the blank to cause the belt to make line contact with the tooth and effecting additional relative movement between the gear tooth and belt to cause the line of engagement therebetween to move between the root and apex of the tooth.

6. The method of grinding gears which comprises moving a flexible belt having abrasive elements thereon along the face of a tooth on a gear blank in a rectilinear path substantially parallel to the axis of the blank and simultaneously rotating the gear on its axis, moving the belt in a direction transverse to the direction of its travel to maintain its engagement with the moving gear tooth, pressing the belt against the face of the moving gear tooth, and then indexing the blank with respect to the belt.

7. A gear grinding apparatus comprising a table for supporting a gear blank, means rotatably mounting said table, a belt having abrasive elements thereon, means for supporting said belt for movement against the face of a gear tooth on said blank in a rectilinear path across the face of the tooth, means on said support for moving said belt, and means for moving said support and rotating the blank in synchronism to effect travel of the belt over the curved surface of the tooth.

8. A gear grinding apparatus comprising a table for supporting a gear blank, means rotatably mounting said table, a belt having abrasive elements thereon, means for supporting said belt for movement against the face of a gear tooth on said blank in a rectilinear path across the face of the tooth, means on said support for moving said belt, means for rotating the blank, and means for moving the support in a direction to cause the belt to follow the face of the tooth during movement of the blank.

9. A gear grinding apparatus comprising a table for supporting a gear blank, means rotatably mounting said table, a belt having abrasive elements thereon, means for supporting said belt for movement against the face of a gear tooth on said blank in a rectilinear path substantially parallel to the axis of the blank, means on said support for moving said belt, means for oscillating said blank, and means for reciprocating said support to cause the belt to follow the face of the tooth during the oscillation of the blank.

10. A gear grinding apparatus comprising a table for supporting a gear blank, means rotatably mounting said table, a belt having abrasive elements thereon, means for supporting said belt for movement against the face of a gear tooth on said blank in a rectilinear path substantially parallel to the axis of the blank, means on said support for moving said belt, means for rotating the blank, means for moving the support in a direction to cause the belt to follow the face of the tooth during movement of the blank, and backing means on the side of the belt opposite that engaged with the gear tooth to hold the belt against the tooth.

11. A gear grinding apparatus comprising a table for supporting a gear blank, means rotatably mounting said table, a belt having abrasive elements thereon, means for supporting said belt for movement against the face of a gear tooth on said blank in a rectilinear path substantially parallel to the axis of the blank, means on said support for moving said belt, means for rotating the blank, means for moving the support in a direction to cause the belt to follow the face of the tooth during movement of the blank, and means to index the gear blank with respect to the belt to effect engagement of the latter with a succeeding tooth on the blank.

12. A gear grinding apparatus comprising a table for supporting a gear blank, means rotatably mounting said table, a belt having abrasive elements thereon, means for supporting said belt for movement against the face of a gear tooth on said blank in a rectilinear path substantially parallel to the axis of the blank, means on said support for moving said belt, means for moving said support in a rectilinear path to move the belt in a direction substantially tangent to the blank, and means connecting said rotatable mounting means for the gear blank to the support to effect rotation of the blank when the support is moved.

13. A gear grinding apparatus comprising a reciprocably mounted carriage, an endless belt having abrasive elements thereon movably mounted on said carriage, means for rotatably mounting a gear blank adjacent the belt, means on the carriage for moving said belt across the face of a gear tooth on the blank in a direction substantially parallel to the axis of the blank, and means for simultaneously rotating the blank and moving the carriage longitudinally to vary the area of engagement of the belt with the face of the tooth.

14. A gear grinding apparatus comprising a reciprocably mounted carriage, an endless belt having abrasive elements thereon movably mounted on said carriage, means for rotatably mounting a gear blank adjacent the belt, means on the carriage for moving said belt across the face of a gear tooth on the blank in a direction substantially parallel to the axis of the blank, means for reciprocating said carriage, and means connecting said carriage to the rotatable mounting means for the gear blank to effect oscillation of the latter upon reciprocation of the carriage.

15. A gear grinding apparatus comprising a reciprocably mounted carriage, an endless belt having abrasive elements thereon movably mounted on said carriage, means for rotatably mounting a gear blank adjacent the belt, means on the carriage for moving said belt across the face of a gear tooth on the blank in a direction substantially parallel to the axis of the blank, means for reciprocating said carriage, means connecting said carriage to the rotatable mounting means for the gear blank to effect oscillation of the latter upon reciprocation of the carriage, and means for disconnecting said connecting means to permit indexing of the blank to engage the belt with a succeeding tooth on the blank.

16. A gear grinding apparatus as in claim 13 wherein the belt is mounted upon a support, and said support is movable transversely of the carriage toward and from the gear blank.

17. A gear grinding apparatus as in claim 13 wherein the belt is mounted upon a support, and said support is mounted upon the carriage for rotative adjustment thereon to vary the angle of the face of the belt with the face of the gear tooth engaged thereby.

18. The method of grinding gears which comprises moving a flexible abrasive belt in the direction of its length over the face of a tooth of a gear blank, rotating the blank, and also moving the belt in the same general direction as the tooth is traveling in the rotation of the blank to maintain the belt in contact with the tooth and efiect its engagement with the tooth over the area of the latter.

19. The method of grinding gears which comprises moving an endless abrasive belt in the direction of its length along the face of a tooth of a gear blank in a direction substantially parallel to the axis of the blank and, during such movement, reciprocating the belt bodily in a direction transverse to the direction of its movement while oscillating the gear blank on its axis in synchronism with the reciprocation of the belt to cause the belt to make contact over the curved face of the tooth.

20. The method of grinding gears as set forth in claim 18 which includes the step of supporting the rear face of the belt to press it against the face of the tooth.

References Cited in the file of this patent UNITED STATES PATENTS Re. 17,884 Copland et al Nov. 25, 1930 1,562,438 Copland Nov. 24, 1925 1,628,531 Carlson May 10, 1927 1,658,899 Hoke Feb. 14, 1928 1,912,216 Page May 30, 1933 2,122,803 Schurr July 25, 1938 2,375,079 Christensen May 1, 1945 2,426,764 Czarnecki Sept. 2, 1947 2,431,822 Murray Dec. 2, 1947 FOREIGN PATENTS 264,625 Great Britain Jan. 27, 1927 

